EP1094294B1 - Linear or angular displacement measuring device - Google Patents

Description

The present invention relates to a measuring device, in particular a comparator for measuring and comparing lengths or angles.

An example of a comparator is shown in Figures 1 and 2. This comparator 1 comprises a frame 2, here of cylindrical shape, and a probing button 3 whose tip 30 is intended to come into contact with the object to be measured or checked. A mechanical measurement system, optoelectronics and / or electronics to determine the position length of the measurement key and display it, for example on a needle dial or LCD display 4. The comparator is generally fitted with one or more sockets 8, 9 of standardized dimensions allowing to fix it to a machine or an external device. Comparators to electronic displays like the one shown are also equipped with a battery compartment 6, manipulation buttons 5, as well that possibly of a serial interface 7, for example an interface optoelectronics.

In the comparator represented in FIGS. 1 and 2, bearings 80, 90 are provided to allow sliding and precise guiding of key 3. In this example, the bearing 90 is machined directly in the upper sleeve 9 while the lower bearing 80 is attached in the lower bush 8.

The comparator shown is provided with a metal case, the external faces of which have undergone a surface treatment for aesthetic reasons in particular. Sealing is only partially ensured thanks to a solid frame 2 and to a bottom 26 screwed or fixed to the notch on this frame and protecting the internal mechanism of the comparator from liquid projections. The device illustrated in FIGS. 1 and 2 must therefore be kept clean to operate and is therefore ill-suited to operation in a humid environment or subject to splashes of dust, lubricant or cutting oil for example. In particular, it is important
ensure that the measuring system inside the comparator is free of any humidity.

CH352497 describes an example of a comparator of this type, including bearings directly attached to the frame.

US5189796 describes another example of a comparator in which the bearings are directly machined in the frame.

An object of the present invention is to provide a comparator improved compared to the comparators of the prior art. A goal of the present invention is also to propose a more economical comparator, more precise, more waterproof, more durable and / or with fewer parts than the comparator illustrated in Figures 1 and 2.

According to the invention, these aims are achieved in particular by bringing the key landing stages closer to each other. The invention therefore suggests using a spacing I between the bearings smaller than the diameter of the case. This characteristic makes it possible to reduce the bending of the touch rod and therefore increase accuracy.

According to another characteristic of the invention, these aims are also achieved by using bearings machined directly in the frame of the comparator. This characteristic makes it possible to reduce the number of parts, and therefore the cost, and decrease the sum of the manufacturing tolerances and assembly of different parts, which also improves the precision. This characteristic also makes it possible to reduce the distance I between the landings.

According to another characteristic of the invention, these aims are also achieved by using a housing covering the external faces of the metal frame of the comparator. The case allows to resolve sealing problems. On the other hand, the housing increases the external diameter of the comparator, and therefore to use an additional display 4 large and easier to read, without having to increase the distance I between bearings which is determined by the diameter of the metal frame. The housing is preferably made of synthetic material and can be maintained by comparator sockets, allowing easy mounting. By disposing it so as to completely cover the metal frame, it is further possible to save the expensive surface treatment of the frame, which reduces costs without having to give up an attractive design.

La figure 1 qui a déjà été décrite, une vue en perspective d'un comparateur ne présentant pas les avantages de l'invention.

La figure 2 qui a déjà été décrite, une vue en coupe d'un comparateur ne présentant pas les avantages de l'invention.

La figure 3, une vue en coupe d'un comparateur selon l'invention.

La figure 4, une vue en perspective d'une touche adaptée à un comparateur selon l'invention.

The invention will be better understood using the description of an exemplary embodiment illustrated by the appended figures which show:

Figure 1 which has already been described, a perspective view of a comparator not having the advantages of the invention.

Figure 2 which has already been described, a sectional view of a comparator does not have the advantages of the invention.

Figure 3, a sectional view of a comparator according to the invention.

Figure 4, a perspective view of a key adapted to a comparator according to the invention.

Figure 3 illustrates a sectional view of a comparator according to the invention. For the readability of the figure, certain elements of the comparator, such as the key (shown in Figure 4) or the measurement system not been represented. The invention in fact applies to any type of system for comparator, for example to purely systems mechanical with needle display, or electronic systems, by capacitive, inductive, optoelectronic or magnetoresistive examples, allowing to display the results for example on a crystal display liquids 4 or to export them via a serial interface, for example a RS232 optoelectronic interface (7).

Comparator 1 makes it possible to determine the position of the end 30 of the probe tip 3 and compare this position with stored reference positions. It includes a metal frame 2 of generally cylindrical shape provided in this example with a bearing upper 23 and a lower bearing 24 for sliding longitudinally the key 3. The bearings are directly machined in the frame 2, in order to reduce the number of parts and the sum of the tolerances of manufacturing and assembly, and therefore increase accuracy while reducing cost and size. This provision also allows reduce the distance 1 between the bearings 23 and 24, in particular to make it well smaller than the external diameter of the comparator housing, and so decrease the bending of key 3 in the measurement zone between the bearings, which improves accuracy.

Depending on the variant, different types of bearings 23 can be used, 24, in particular stony bearings and / or fitted with an oil tanker ensuring optimal sliding. The invention also applies to comparators in which the key only crosses the frame at a single point, and therefore fitted with a single bearing. The invention also relates to the variants of less advantageous comparator which are provided with two bearings, but only one of which is machined directly in the frame 2.

A lower sleeve 8 is integrally connected to the frame 2, by for example by screwing, gluing or chasing. This socket is optional and could be absent depending on the variant carried out. In a variant not illustrated, the upper sleeve 9 could also be made of material synthetic, for example integrated into the housing 10 or the cover 11 described lower. The lower sleeve 8 is provided with a through opening 82 for the passage of the key 3, the diameter of the opening 82 being slightly greater than the internal diameter of the lower bearing 24. The socket lower 8 thus does not participate in guiding the button 3, so that its machining and fixing constraints to the frame 2 are less critical. The socket 8 allows the comparator to be attached to external devices, by example to machines or along an assembly line.

Similarly, in the example illustrated, an upper sleeve 9 is integrally connected to the frame 2, for example by screwing, gluing or chassage. This socket is optional and may be missing depending on the variant performed. In a variant not illustrated, the upper sleeve 9 could also be made of synthetic material, for example integrated to the housing 10 or to the cover 11 described below. In the same way as for the lower sleeve 8, the upper sleeve 9 is provided with a through opening 92 with a diameter slightly greater than the diameter internal of the bearing 23, and thus not participating in guiding the button.

The key 3 is shown in perspective in Figure 4. It essentially comprises a cylindrical body whose diameter is machined precisely, in order to avoid any lateral play in the bearings 23 and 24. The end of the key is provided with a touch point 30, the shape and hardness can be adapted to the use, the tip 30 which can in a preferential variant be unscrewed by grasping it by a portion 31 to replace it with a more appropriate tip.

In the illustrated variant, a movable portion 33 of a circuit position determination electronics is securely attached to the key 3, so as to collaborate with a fixed part not shown and linked to frame 2 of the measurement circuit. The relative position of the moving part 33 and the fixed part can be determined and compared with a value of stored reference, and the result displayed on display means digital 4. The measurement system can be capacitive, inductive, magnetoresistive or optoelectronic for example, the invention not being limited to these examples and can also be applied to fully mechanical comparators. In the case of a capacitive system or magnetoresistive, the fixed part will for example consist of a flat sensor mounted at a short distance opposite the sliding rule 33 provided with respectively magnetic capacitive electrodes. In the case of an electro-optical system, the measurement system will include example a light emitter sending through one or more lenses a light beam through the graduated rule 33 as well as a sensor optical system reacting to light transmitted or reflected by the rule.

The button 3 is provided with a guide portion 32 collaborating with a guide slot 20 machined or attached in the internal wall of the frame, in order to prevent the rotation of the key on its own axis. A stop 21, into which can be screwed a screw 22 screwed from the front face of the comparator, makes it possible to limit the longitudinal displacement of the key 3 and to prevent the rule 33 from coming into contact with the frame.

The frame 2 of the comparator is covered by a housing 10 in synthetic material or possibly stamped sheet metal, which covers preferably all the external faces 25 of the frame and also closes the bottom. The case 10 protects the comparator from shocks and infiltration liquid, and give it an attractive design. In order to limit the number parts and water infiltration points, preferably use a case made in one piece. According to the invention, the housing 10 is held on the frame 2 by the sockets 8 and 9 inserted in openings 102, 103 through the housing 10. The comparator is thus assembled in placing the metal frame 2 at the bottom of the housing 10, then passing the sockets 8, 9 through the openings 102, 103 in order to assemble them to the frame. A circular joint 81 is preferably provided to prevent liquid or vapor infiltration between the lower bush 8 and the housing 10; in the same way, a circular joint 91 may be disposed between the upper sleeve 9 and the housing 10. Screws or deformable elements elastically not shown may alternatively be provided in different places of the case in order to prevent for example that the bottom of the housing 10 does not move.

The comparator is further provided with a cover 11 mounted on the case 10 and closing the front face. The cover 11 will itself be preferably made of synthetic material and provided with a visible display 4 through an optional glass 100 and welded or glued tightly in an opening through the cover 11. The cover 11 will be example screwed, glued, welded or preferably held by deformation elastic on the housing 10, an O-ring 101 can be provided for prevent infiltration of liquid or liquid vapor. Stubborn not shown is intended to prevent rotation of the cover by report to the housing. In a variant not shown, the cover 11 is on the contrary rotating relative to the housing 10, in order to be able to restore the horizontality of display 4 even when the comparator is not installed in vertical position. In this case, display 4 is preferably connected to the electronic measurement system not represented by a mat flexible cables not shown. How the comparator works display 4 are controlled by function keys not shown on the cover and / or on the housing 10, and which allow by example of selecting the unit of measurement or storing positions reference. For example, use function keys in soft elastomer compressed into corresponding openings through the housing 10 and / or the cover 11, so as to guarantee sealing.

In a variant not shown, the junction between the housing and the cover is oblique, so that the case is held by the socket lower and the cover by the upper sleeve (or vice-versa).

The comparator preferably further comprises an output serial not shown, for example a connection plug allowing insert an optoelectronic socket. A battery compartment, for example for a lithium battery, will be further provided for example in side walls of the comparator, so as to allow replacement of the battery by opening the compartment, without the need to disassemble the plastic housing 10 or even remove the cover 11. Des suitable seals will be provided at the battery compartment and possibly the opto-electronic interface.

The comparator can be delivered with a cap not shown and intended to be inserted over the upper sleeve 9 for prevent liquid from entering through this socket. A joint may be provided between the socket 9 and the cap. A non-extendable bellows shown may also be provided over the lower sleeve 8 and key 3 to avoid liquid infiltration through the opening 82.

The housing 10 and the various seals described above allow obtain a comparator with a protection index according to the standard DIN40050 for example equal to IP54, i.e. protected against dust (no harmful deposit) and protected against liquid splashes from all directions. Other means could be imagined in the context of this invention to further improve the sealing of the internal volume of the comparator. For example, a valve allowing air to pass through but retaining liquid vapors and dust can be used to balance internal pressure and external atmospheric pressure. A desiccant capsule can also be placed inside the comparator in order to absorb the liquids entered, for example in the form of steam.

Those skilled in the art will understand that type comparators, of very different shapes and sizes can be made as part of this invention, as well as other types of devices similar for measuring and comparing lengths, depths, angles, diameters, etc.

Claims (14)

1. Dial indicator for measuring and comparing linear or angular dimensions, comprising:

   a metallic casing (2),

   at least one bearing (23, 24) intended to accommodate a sensing probe (3) going through said casing (2),

   at least one socket (8, 9) integral with the casing (2),

   a measuring system comprising a mobile portion (33) driven by said sensor probe and a fixed portion integral with the casing, characterized by

   a housing (10) covering the outer sides (25) of said casing (2) and held by said at least one socket (8, 9).
2. Dial indicator according to the preceding claim, wherein said outer sides (25) of the casing (2) are entirely covered by said housing (10).
3. Dial indicator according to one of the preceding claims, wherein a gasket (81, 91) is provided between said housing (10) and said at least one socket (8, 9).
4. Dial indicator according to one of the preceding claims, fitted further with a cover (11) fastened to said housing (10).
5. Dial indicator according to the preceding claim, a gasket (101) being provided between said housing (10) and said cover (11).
6. Dial indicator according to one of the claims 4 or 5, said cover (11) bearing a display (4) and able to pivot in relation to said casing (2).
7. Dial indicator according to one of the preceding claims, comprising a lower socket (8) and an upper socket (9), both integral with the casing (2), said housing (10) being held by both sockets (8, 9).
8. Dial indicator according to one of the preceding claims, further comprising fastening screws of said housing onto said casing.
9. Dial indicator according to one of the preceding claims, wherein said at least one socket (8, 9) has been made integral with said casing (2) by passing through an opening (102, 103) of said housing (10) after the latter has been mounted onto the casing (2).
10. Dial indicator according to one of the preceding claims, wherein said at least one bearing (23, 24) is machined or fastened directly into the casing (2).
11. Dial indicator according to claim 10, comprising a lower bearing (24) and an upper bearing (23), both being worked or fastened directly into the casing (2).
12. Dial indicator according to the preceding claim, wherein the distance (I) between the lower bearing (24) and the upper bearing (23) is less than the inner diameter of said housing (10).
13. Dial indicator according to the preceding claim, comprising a lower socket (8) and an upper socket (9), both integral with the casing (2).
14. Dial indicator according to the preceding claim, wherein the distance (I) between the lower bearing (24) and the upper bearing (23) is less than the distance between said lower socket (8) and said upper socket (9).

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